What is "actualism"

n. (context philosophy English) Belief that actuality and existence are co‐extensive: i.e., that only actual things exist, that there are not, in addition to the actual, any possibility (possible entities).

In contemporary analytic philosophy, actualism is a position on the ontological status of possible worlds that holds that everything that exists (i.e., everything there is) is actual. Another phrasing of the thesis is that the domain of unrestricted quantification ranges over all and only actual existents.

The denial of actualism is possibilism, the thesis that there are some entities that are merely possible: these entities exist (in the same way that ordinary objects around us do) but are not to be found in the actual world. Regarding modal realism: "An important but significantly different notion of possibilism to which many of the issues in this article do not apply was developed by the philosopher David Lewis."